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Procedure

Nerve Root Injection

During a Nerve Root Injection procedure, the therapeutic substance is administered directly to the affected nerve root. This treatment is specifically targeted for cases involving inflammation, such as acute or chronic sciatica, with or without root signs. Common symptoms include painful flexion, side flexion away from pain, and nerve root tension signs.

The lumbar nerve roots exit diagonally from the vertebral canals, situated between the transverse processes at the same level as the spinous process. Visualize a vertical line running through the center of the spinous processes, and draw horizontal lines aligned with each spinous process.

Approximately one thumb’s width away from the horizontal line, in a lateral direction, indicates the approximate insertion point for the needle.

See Also: Spondylolisthesis: Causes, Symptoms & Treatment

Equipment Needed

  • Syringe: 1 ml
  • Needle: Spinal, 22 gauge / 3–4 inches (75–90 mm)
  • Kenalog 40: 40 mg
  • Total volume: 1 ml

Nerve Root Injection Technique

  • Begin by positioning the patient in a prone position with a small pillow to help locate the spinous processes.
  • Locate the spinous process at the level of pain and mark a spot laterally along a horizontal line.
  • Insert a needle perpendicular to the skin to a depth of approximately 3 inches (7 cm).
  • Perform aspiration to confirm that the needle tip is not in the intrathecal space or a blood vessel.
  • Administer the solution as a bolus around the nerve root.

The patient keeps mobile within pain limits and is reassessed a week or 10 days later. Repeat Nerve Root Injection as necessary.

Nerve Root Injection Technique

Notes

This injection can provide significant relief, particularly in cases of severe pain where conventional manual therapy techniques are not feasible. It can also be considered when previous attempts at caudal epidural injection have been unsuccessful. Although the caudal technique is technically simpler, there is a possibility that the solution may not effectively reach the affected area of the nerve root. If the initial injection does not alleviate the symptoms, alternative levels above or below can be targeted, which is a worthwhile approach before considering surgical options.

If the needle encounters bone at approximately 2 inches (≈5 cm), indicating contact with the lamina or facet joint, it must be repositioned. Similarly, if the patient experiences a sharp electric shock sensation, indicating contact with the nerve root, needle repositioning is necessary. It is possible to infiltrate two levels simultaneously, although a longer needle may be required for larger patients.

In the event of clear fluid aspiration, indicating an intrathecal needle position, the procedure must be halted, although it can be attempted again after a few days.

Study: Therapeutic selective nerve root block (SNRB Injection) is an important procedure in the pain management of patients with lumbar radiculopathy caused by lumbar disc prolapse and foraminal stenosis. This study showed that avoidance of surgery was achieved in up to 54% of patients; pain relief for at least 6 months was achieved in up to 29% of patients after a single selective nerve root block. This makes it a very good second line of management after conservative treatment and a possible method to delay, and sometimes cease, the need for surgery.

selective nerve root block
Fluoroscopic image of the lumbar spine in lateral view showing the tip of needle positioned at the upper part of the L4 foramen and dye flowing around the nerve root within the foramen.

References & More

  1. Injection Techniques in Musculoskeletal Medicine. A Practical Manual for Clinicians In Primary And Secondary Care. Fifth Edition
  2. Kanaan T, Abusaleh R, Abuasbeh J, Al Jammal M, Al-Haded S, Al-Rafaiah S, Kanaan A, Alnaimat F, Khreesha L, Al Hadidi F, Al-Sabbagh Q. The Efficacy of Therapeutic Selective Nerve Block in Treating Lumbar Radiculopathy and Avoiding Surgery. J Pain Res. 2020 Nov 18;13:2971-2978. doi: 10.2147/JPR.S276331. PMID: 33239905; PMCID: PMC7680787. [Pubmed]
  3. Eckel TS, Bartynski WS. Epidural steroid injections and selective nerve root blocks. Tech Vasc Interv Radiol. 2009 Mar;12(1):11-21. doi: 10.1053/j.tvir.2009.06.004. PMID: 19769903. [Pubmed]
  4. Eastley NC, Spiteri V, Newey ML. Variations in selective nerve root block technique. Ann R Coll Surg Engl. 2013 Oct;95(7):515-8. doi: 10.1308/003588413X13629960048073. PMID: 24112500; PMCID: PMC5827280. [Pubmed]
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